The Court’s decision was unanimous in Hosanna-Tabor. Given some of the language in Chief Justice Roberts’ decision, I find that rather surprising — particularly because some thought that there was a reasonable chance that we would see multiple opinions in this case going in all sorts of directions.
Unanimity in religion clause cases is uncommon. In part that’s because they tend generally to be fairly controversial, in part because (as Greg Sisk and Michael Heise have shown) they tend to map onto a Justice’s political ideology (not always, but fairly often). Unanimity as to the judgment happens once in a while. Unanimity as to the judgment and the reasoning is extremely rare.
There have been two relatively recent unanimous opinions involving religion, or at least functionally unanimous opinions, and both are Roberts Court decisions, but neither of them is a religion clause decision. They are Gonzales v. O Centro Espirita Beneficente Do Vegetal in 2006 and Cutter v. Wilkinson in 2005. Those cases dealt with the operation of RFRA and RLUIPA respectively and were widely seen as relatively uncontroversial.
But as to the religion clauses, what was the last unanimous decision? There was unanimity as to the judgment in Church of the Lukumi Babalu Aye v. City of Hialeah, but the concurring opinions did not sign on to the reasoning of Justice Kennedy. Justices Blackmun and O’Connor wrote separately to voice disagreement with the Smith decision, on the basis of which Lukumi was decided. Likewise, there was unanimity as to the judgment in Lamb’s Chapel v. Center Moriches Union Free School Dist., but the concurrences largely rejected the reasoning of the Court.
So far as I can tell, the last unanimous religion clause decision was in 1990: Jimmy Swaggart Ministries v. Bd. of Equalization of California, which dealt with the issue whether a sales and use tax imposed by the state of California violated the religion clauses. The Court held against the religious claimant there.
The Court was also unanimous in 1989 in Frazee v. Illinois Dept. of Employment, an unemployment compensation decision in which the religious claimant won following the Sherbert test.
Before that, one has to go back all the way to U.S. v. Seeger in 1965…except that Seeger also was not about the religion clauses! It was a case interpreting the Universal Military Training and Service Act.
Before that…it may be that Cantwell v. Connecticut way back in 1940 was the last unanimous religion clause decision in which everyone signed onto the reasoning of the opinion.
Leaving us with: Cantwell, Frazee, Jimmy Swaggart. And now, Hosanna-Tabor.